TCTAP 2026
Carotid Artery Near Occlusion: Current Evidence and Practice
Carotid artery near occlusion (CANO) had long remained a difficult gray zone in carotid intervention. At TCTAP 2026, Hsien-Li Kao, MD (National Taiwan University Hospital, Taiwan), reviewed the current evidence and his practical approach to this challenging lesion. His central message was that CANO was not simply severe carotid stenosis or complete occlusion, but a distinct delayed-flow state caused by critical stenosis that required careful diagnosis and individualized revascularization planning. Defining CANO Beyond Percent Stenosis He defined CANO as severe carotid stenosis with reduced distal internal carotid artery (ICA) flow. He noted that the same entity had been described historically by terms such as the “string sign,” “pseudo‑occlusion,” “pre‑occlusive stenosis,” and “hairline residual lumen.” Diagnosis was considered when at least two of four angiographic criteria were present: delayed filling of the distal ICA, intracranial collateral flow, an ipsilateral distal ICA smaller than the contralateral distal ICA, and an ipsilateral distal ICA equal to or smaller than the ipsilateral external carotid artery (ECA). Why Distal Lumen Collapse Mattered A key point of the presentation was the distinction between CANO with and without distal ICA collapse. Full collapse was defined as a distal ICA diameter of 2.0 mm or less and/or an ipsilateral‑to‑contralateral distal ICA diameter ratio of 0.42 or less (Neuroradiology 2022;64:59‑67). He emphasized that this distinction was clinically relevant because near‑occlusion with collapse carried a higher risk of recurrent ipsilateral stroke and should not have been grouped uncritically with non‑collapsed near‑occlusion. He proposed a working classification that placed near occlusion as an intermediate state between conventional stenosis and total occlusion, with collapse and non‑collapse as further subgroups (Figure 1). Figure 1. Working classification of carotid stenosis, with near occlusion further divided into “with collapse” and “without collapse.” Adapted from his TCTAP 2026 presentation; collapse criteria from Neuroradiology 2022;64:59‑67. Representative digital subtraction angiograms (Figure 2) further illustrated the spectrum: CANO with collapse showed a thread‑like distal ICA, CANO without collapse retained a near‑normal distal caliber despite a critical proximal lesion, and conventional carotid stenosis showed a focal lesion without distal hemodynamic compromise. Figure 2. Representative carotid angiograms. (A) CANO with distal lumen collapse; (B) CANO without collapse; (C) conventional non-CANO carotid stenosis. Asterisks mark the ICA bulb; arrows mark the lesion. Adapted from his TCTAP 2026 presentation. Evidence Remained Limited The evidence base remained thin because CANO had been excluded from, or poorly represented in, the landmark randomized carotid trials that shaped routine practice (NASCET, ECST, CREST, and ICSS). Although small near‑occlusion subgroups appeared in NASCET and ECST analyses (Am J Neuroradiol 2005;26:2086‑94), he stressed that these were old CEA‑era data with limited case numbers rather than dedicated CANO trials. More recent evidence suggested that best medical therapy alone might not have been sufficient for some patients (Br J Surg 2019;106:665‑71), particularly those with distal collapse and recurrent symptoms (J Neurol 2020;267:522‑30). The 2023 ESVS guideline recommendation was also cautious: revascularization could be considered for patients with carotid near occlusion and distal vessel collapse who had recurrent carotid‑territory symptoms despite best medical therapy, but only after multidisciplinary team review (Eur J Vasc Endovasc Surg 2023;65:7‑111). Periprocedural Safety of CAS To address whether carotid artery stenting (CAS) for CANO was inherently risky, he reviewed his group’s experience published in Scientific Reports in 2021 (Sci Rep 2021;11:21876). The cohort compared 92 CANO patients with 106 age‑ and sex‑matched patients who had conventional 70% to 99% carotid stenosis. Full distal collapse was present in 45 of the 92 CANO patients. Despite longer target‑lesion length and a higher symptomatic‑disease rate in the collapse subgroup, the technical success rate was 100%, and the 30‑day safety outcomes were comparable between CANO and conventional stenosis (Table 1). Table 1. Thirty‑Day Outcomes After CAS in CANO Versus Conventional Carotid Stenosis Outcome CANO (N = 92) Conventional (N = 106) P value Hyperperfusion syndrome 2 (2.2%) 1 (0.9%) 0.598 Ischemic stroke 1 (1.1%) 2 (1.9%) 1.000 Major ipsilateral stroke 1 (1.1%) 1 (0.9%) 1.000 Mortality 0 (0.0%) 1 (0.9%) 1.000 All stroke and mortality 1 (1.1%) 2 (1.9%) 1.000 CAS = carotid artery stenting; CANO = carotid artery near occlusion. Data were adapted from the TCTAP 2026 presentation and Sci Rep 2021;11:21876. Technical Approach The case‑based portion of the talk illustrated why the procedure remained technically demanding. He showed careful lesion crossing with an 8‑Fr JR4 guiding catheter, a Fielder FC guidewire supported by a Finecross microcatheter, and distal embolic protection with a Spider device. In the 2021 cohort, embolic protection was used in 98% of CANO cases. Predilatation before stent deployment was more frequent in CANO than in conventional stenosis (30% vs. 11%; P = 0.001), and predilatation before embolic‑protection‑device placement was used more often in the collapse subgroup, reflecting the challenge of safely passing devices through a thread‑like residual lumen. Long‑Term Perspective He also cited long‑term data from his group (Eur J Radiol 2025;191:112297) and a smaller independent cohort (Am J Neuroradiol 2022;43:1311‑17). These reports suggested that long‑term outcomes after CAS were comparable with those after stenting for conventional severe carotid stenosis. However, the evidence remained observational, and the presentation repeatedly underscored the need for prospective dedicated data. Conclusions He concluded that CANO was neither ordinary carotid stenosis nor complete occlusion, but a delayed‑flow state caused by critical stenosis. CANO was associated with a high recurrent-stroke risk, especially when distal lumen collapse was present. CEA was described as inherently difficult in this anatomy, and CAS appeared feasible and safe in experienced centers, with a potential role in selected patients with CANO and distal collapse. The key remaining question was not whether CANO deserved attention, but which patients would benefit most from revascularization — a question that still required prospective study. Hot Topics Practical Approaches to Stroke, Carotid, and Peripheral Interventions Friday, May 1, 4:20 PM ~ 5:40 PM Presentation Theater 2, Level 1
June 11, 2026 6955
